Given:
Amount after 3 years = ₹9,430
Amount after 7 years = ₹11,070
Find interest for 4 years
11070−9430=1640
So, interest for 4 years = ₹1640
Interest per year
41640=410
Find Principal
Amount after 3 years = ₹9,430
P+3×410=9430
P+1230=9430
P=9430−1230=8200
₹8,200